Unified Services Router User Manual
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Appendix A. Glossary
Address Resolution Protocol. Broadcast protocol for mapping IP addresses to MAC addresses.
Challenge-Handshake Authentication Protocol. Protocol for authenticating users to an ISP.
Dynamic DNS. System for updating domain names in real time. Allows a domain name to be
assigned to a device with a dynamic IP address.
Dynamic Host Configuration Protocol. Protocol for allocating IP addresses dynamically so that
addresses can be reused when hosts no longer need them.
Domain Name System. Mechanism for translating H.323 IDs, URLs, or e-mail IDs into IP
addresses. Also used to assist in locating remote gatekeepers and to map IP addresses to
hostnames of administrative domains.
Fully qualified domain name. Complete domain name, including the host portion. Example:
serverA.companyA.com.
File Transfer Protocol. Protocol for transferring files between network nodes.
Hypertext Transfer Protocol. Protocol used by web browsers and web servers to transfer files.
Internet Key Exchange. Mode for securely exchanging encryption keys in ISAKMP as part of
building a VPN tunnel.
IP security. Suite of protocols for securing VPN tunnels by authenticating or encrypting IP
packets in a data stream. IPsec operates in either transport mode (encrypts payload but not
packet headers) or tunnel mode (encrypts both payload and packet headers).
Internet Key Exchange Security Protocol. Protocol for establishing security associations and
cryptographic keys on the Internet.
Internet service provider.
Media-access-control address. Unique physical-address identifier attached to a network
adapter.
Maximum transmission unit. Size, in bytes, of the largest packet that can be passed on. The
MTU for Ethernet is a 1500-byte packet.
Network Address Translation. Process of rewriting IP addresses as a packet passes through a
router or firewall. NAT enables multiple hosts on a LAN to access the Internet using the single
public IP address of the LAN’s gateway router.
Microsoft Windows protocol for file sharing, printer sharing, messaging, authentication, and
name resolution.
Network Time Protocol. Protocol for synchronizing a router to a single clock on the network,
known as the clock master.
Password Authentication Protocol. Protocol for authenticating users to a remote access server
or ISP.
